1. Field of the Invention
This invention pertains to conveyors, and more particularly, it relates to a conveyor for advancing empty egg cartons made of thin flexible material past a station where eggs are discharged vertically into the cartons.
2. Background of the Invention
Conveyors for advancing empty egg cartons by a station where eggs are dropped into the cartons qre well known in the egg handling field. A typical form of such a conveyor is disclosed in prior U.S. Pat. No. 3,447,282, issued to Harold J Mumma on June 3, 1969, which patent discloses an endless chain conveyor structure including a plurality of upright pusher members spaced along the chain for individually engaging egg cartons and sliding the cartons between a pair of longitudinally extending bars or rails. Cartons normally handled by such a conveyor are made of paper mache, plastic or cardboard and have sufficient stiffness to support the eggs while spanning transversely between spaced supporting surfaces. Such cartons also have an inherent resiliency that enables the egg receiving pockets to yield internally and thereby cushion or absorb the shock of an egg as it is received in a pocket.
A form of egg carton currently used in Japan and contemplated for use in other areas of the world is made of polyvinylchloride having a thickness of about 0.005 inches. The carton is transparent to allow the eggs to be viewed within a closed carton, and the carton is very light and flexible. There are two rows of pockets in the carton with five pockets in each row. When the pockets of such cartons are resting upon a support surface, there is not sufficient internal yielding of the pocket to absorb the shock of an egg dropped therein, and the shock reaction resulting from the falling egg striking the carton pocket can break the egg. Such cartons also do not have sufficient stiffness to serve as a beam to support eggs while spanning a distance that is a significant portion of the length of the carton, nor do they have sufficient mass to provide stability against overturning if eccentrically loaded with eggs and subjected to deceleration forces or if unloaded and subjected to gusts of wind or acceleration forces. Thus, the egg carton conveyor disclosed in the previously mentioned U.S. Pat. No. 3,447,282 does not satisfactorily handle thin plastic cartons, such as those currently used in Japan. Other prior art carton conveyors suffer similar defects and have not proven to be effective in handling the aforementioned thin, flimsy cartons.